Alfalfa is a critical forage crop for livestock and an important component of crop rotations as a nitrogen fixing perennial crop. Canada is a major producer of alfalfa seed, where most of the production occurs in the Prairie provinces. Growers face numerous insect pests that vary from year-to-year and field-to-field. Alfalfa seed in western Canada depends on insecticides for the control of insect pests and on alfalfa leafcutter bees for pollination. Therefore producers must balance crop protection and pollinator health. This study aimed to better understand how management practices, including insecticide applications, and regional weather conditions influence insect pests populations and yield in southern Alberta. Between 2023 and 2024, 17 alfalfa seed fields were monitored. Sweep samples were collected from four areas in each field, each containing paired insecticide treated and untreated plots (90m x 30m). Pest communities varied within and between fields. Insecticide applications impact the insect pest communities, with many interactions between insecticide mode of actions, application timing, and late season pest management. Different combinations of insect pests had different degrees of yield losses, with Miridae insects typically under managed while causing significant yield losses comparable to alfalfa weevil. Insecticide applications generally increased yields, particularly with high pressure from multiple insect pests. Overall variation in insect pest pressures makes on-farm decision making complex and requires close monitoring of insects throughout the growing season and the development of multi-pest action thresholds.